I down loaded tmobile trust cert. throught my 9100 using my home wi-fi. This is the website that I use to download the file since the link posted by John is no longer available: ( sorry I cannot post a link)

twoeighteighty.com

Until I reached procedure no. 13 on Johns guide, I cannot find tmobile trust cert, I scrolled down from top to bottom but nothing, and there's no option to search for a file.